Land Use Requirement of Sorghum on Swell-Shrink Soils Based on Its Performance at Varied Management

In field trials, the influence of soil and land-scape characteristics under two management levels (Low.and optimum) on sorghum were studied. Soil erosion and drainage, among the site parameters and soil depth, per cent clay, plant available water holding capacity (PAWC), length of growing period (LGP of soil) and cation exchange capacity (CEC) among the soil parameters were the important yield Colltributors. Under stressed management (i.e. low management level), the importance of these above parameters was found conspicuous in determining the yield of sorghum. For achieving maximum yield, the optimum values from the fitted quadratic curves were worked out to be 1.55 m of soil depth, >35% of clay (but for 25% sand), 257 rom of PAWC and > 55 cmol (p⁺) kg⁻¹ of CEC. As per the nature of relationship of soil parameters with grain yield and based on the optimum or critical values, the soil-site requirements have been defined for sorghum. At optimum crop management level, among the 15 multiple linear regression (MLR) models established by least square technique, model no. IX (yield =33.88 + 1.413 erosion ratings -4.425 drainage ratings -0.517 silt % + 0.410 clay % 8.557 organic carbon % + 0.268 CaCO₃ % + 0.097 PAWC in rom -0.134 LGP in days) was more reliable in forecasting the yield. The eight soil parameters in the above model explained 60 per cent (R²= 0.601) variability in yield in swell-shrink s.oils. At low crop management level, MLR model no. XI (yield = -12.21 + 1.946 drainage ratings -0.260 sand % -0.464 silt % + 0.139 CaCO₃% + 21.09 ECe in dS m⁻¹ + 4.314 pH) appeared to be more accurate R2 = 0.567). However, the user can adopt any of the models developed Ul)der each management levels, except the non-significant ones, for predicting the yield of sorghum.